I saw the same product advertised in TOH magazine. They are 24"x24" tongue-and-groove panels of OSB with a synthetic membrane on the bottom with little bumps or feet that keep the panel elevated off the concrete. The advertisement indicated a 7/8" thickness, and a $6/panel price (a bit high, but probably worth it if you consider the possibility of replacing carpeting!).
If I remember the brand name or find the mag, I will post-up again.